Organic light-emitting diode display including a storage capacitive plate and a driving voltage line formed on the same layer and manufacturing method thereof

ABSTRACT

An OLED display and a method of manufacturing thereof are disclosed. In one aspect, the display includes a scan line formed over a substrate and configured to transfer a scan signal, a data line and a driving voltage line crossing the scan line and respectively configured to transfer a data voltage and a driving voltage, and a switching transistor electrically connected to the scan line and the data line and including a switching drain electrode configured to output the data voltage. The display also includes a driving transistor including a driving gate electrode, a driving drain electrode, and a driving source electrode electrically connected to the switching drain electrode. The display further includes a storage capacitor including a first storage electrode electrically connected to the driving gate electrode and a second storage electrode formed on the same layer as the driving voltage line.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/985,376, filed on Aug. 5, 2020 in the U.S. Patent and Trademarkoffice, which is a continuation of U.S. patent application Ser. No.15/867,600, filed on Jan. 10, 2018 in the U.S. Patent and TrademarkOffice, which is a divisional of U.S. patent application Ser. No.14/708,049, filed on May 8, 2015 in the U.S. Patent and TrademarkOffice, which claims priority from and the benefit of Korean PatentApplication No. 10-2014-0161932, filed in the Korean IntellectualProperty Office on Nov. 19, 2014, the contents of all of which areherein incorporated by reference in their entireties.

BACKGROUND Technical Field

The described technology generally relates to an organic light-emittingdiode display and a manufacturing method thereof.

Description of the Related Technology

An organic light-emitting diode (OLED) display includes two electrodesand an organic emission layer positioned therebetween. An electroninjected from one electrode and a hole injected from the other electrodeare combined in the organic emission layer to generate an exciton, andthe exciton emits energy in the form of light.

An OLED display includes a matrix of pixels. In each pixel, a pluralityof thin film transistors (TFTs) and at least one storage capacitor fordriving the OLED are formed. The TFTs include a switching TFT and adriving TFT.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

One inventive aspect is an OLED display and a manufacturing methodthereof having advantages of changing a pixel structure of the OLEDdisplay to manufacture the OLED display by using at least one less mask.

Another aspect includes an OLED display including: a substrate; a scanline formed on the substrate and transmitting a scan signal; a data lineand a driving voltage line crossing the scan line and respectivelytransmitting a data voltage and a driving voltage; a switchingtransistor connected to the scan line and the data line and including aswitching drain electrode outputting the data voltage; a drivingtransistor including a driving source electrode connected to theswitching drain electrode; a storage capacitor including a first storageelectrode connected to a driving gate electrode of the drivingtransistor and a second storage electrode that is a part of the drivingvoltage line; and an OLED electrically connected to a driving drainelectrode of the driving transistor.

The first storage electrode and the driving gate electrode can overlapeach other.

A gate connecting member formed with the same layer as the scan line canbe further included, the driving voltage line can include a firstdriving voltage line parallel to the data line and a second drivingvoltage line crossing the data line, the data line can include an upperdata line and a lower data line separated from each other in a crossingportion crossing the second driving voltage line, and the gateconnecting member can connect the upper data line and the lower dataline to each other.

The gate connecting member can cross the second driving voltage line.

A semiconductor formed on the substrate and including a switchingchannel and a driving channel separated from each other, a first gateinsulating layer covering the semiconductor, and a switching gateelectrode and a driving gate electrode formed on the first gateinsulating layer and respectively overlapping the switching channel andthe driving channel can be further included, and the gate connectingmember can be formed with the same layer as the switching gate electrodeand the driving gate electrode.

The driving channel can have at least one curved portion.

A second gate insulating layer covering the switching gate electrode,the driving gate electrode, and the gate connecting member, aninterlayer insulating layer covering the data line and the drivingvoltage line, and a passivation layer formed between the interlayerinsulating layer and the OLED can be further included, and the data lineand the driving voltage line can be formed between the second gateinsulating layer and the interlayer insulating layer.

The first storage electrode and the driving gate electrode can beseparated from each other in a plane.

A semiconductor formed on the substrate and including a switchingchannel and a driving channel separated from each other, a first gateinsulating layer covering the semiconductor, a switching gate electrodeand a driving gate electrode formed on the first gate insulating layerand respectively overlapping the switching channel and the drivingchannel, and a second gate insulating layer covering the switching gateelectrode and the driving gate electrode can be further included, and athickness of the second gate insulating layer positioned between thefirst storage electrode and the second storage electrode can be thinnerthan the thickness of the second gate insulating layer formed on thedriving gate electrode.

An interlayer insulating layer covering the data line and the drivingvoltage line and a passivation layer formed between the interlayerinsulating layer and the OLED can be further included, and the data lineand the driving voltage line can be formed between the second gateinsulating layer and the interlayer insulating layer.

Another aspect is a manufacturing method of an OLED display including:forming a semiconductor on a substrate; forming a first gate insulatinglayer on the semiconductor; forming a driving gate electrode, aswitching gate electrode, and a gate connecting member on the first gateinsulating layer; forming a second gate insulating layer covering thedriving gate electrode and the switching gate electrode; simultaneouslyforming a data line including an upper data line and a lower data lineseparated from each other, a first driving voltage line parallel to thedata line, and a second driving voltage line crossing the data line onthe second gate insulating layer; forming an interlayer insulating layercovering the data line, the first driving voltage line, and the seconddriving voltage line; and forming an OLED on the interlayer insulatinglayer; wherein the gate connecting member connects the upper data lineand the lower data line to each other.

Forming a passivation layer can be further included after forming theinterlayer insulating layer.

A storage capacitor can be formed in a region where the driving gateelectrode and an expansion region of the first driving voltage lineoverlap.

The driving channel can have at least one curved portion.

Another aspect is an organic light-emitting diode (OLED) displaycomprising a substrate, a scan line formed over the substrate andconfigured to transfer a scan signal, a data line and a driving voltageline crossing the scan line and respectively configured to transfer adata voltage and a driving voltage, and a switching transistorelectrically connected to the scan line and the data line and includinga switching drain electrode configured to output the data voltage. Thedisplay also includes a driving transistor including a driving gateelectrode, a driving drain electrode, and a driving source electrodeelectrically connected to the switching drain electrode. The displayfurther includes a storage capacitor including a first storage electrodeelectrically connected to the driving gate electrode and a secondstorage electrode formed on the same layer as the driving voltage line.Furthermore, the display includes an OLED electrically connected to thedriving drain electrode.

In the above display, the first storage electrode and the driving gateelectrode at least partially overlap each other.

The above display further comprises a gate connecting member formed onthe same layer as the scan line, wherein the driving voltage lineincludes a first driving voltage line substantially parallel to the dataline and a second driving voltage line crossing the data line, whereinthe data line includes an upper data line and a lower data lineseparated from the upper data line, and wherein the gate connectingmember is configured to electrically connect the upper data line to thelower data line.

In the above display, the gate connecting member crosses the seconddriving voltage line.

The above display further comprises a semiconductor layer formed overthe substrate and including a switching channel and a driving channelseparated from each other, a first gate insulating layer at leastpartially covering the semiconductor layer, and a switching gateelectrode and a driving gate electrode formed over the first gateinsulating layer and at least partially overlapping the switchingchannel and the driving channel, respectively, wherein the gateconnecting member is formed on the same layer as the switching gateelectrode and the driving gate electrode.

In the above display, the driving channel has at least one curvedportion.

The above display further comprises a second gate insulating layer atleast partially covering the switching gate electrode, the driving gateelectrode, and the gate connecting member. The above display furthercomprises an interlayer insulating layer at least partially covering thedata line and the driving voltage line and a passivation layer formedbetween the interlayer insulating layer and the OLED, wherein the dataline and the driving voltage line are formed between the second gateinsulating layer and the interlayer insulating layer.

In the above display, the first storage electrode and the driving gateelectrode are separated from each other.

The above display further comprises a semiconductor layer formed overthe substrate and including a switching channel and a driving channelseparated from each other and a first gate insulating layer at leastpartially covering the semiconductor layer. The above display furthercomprises a switching gate electrode and a driving gate electrode formedover the first gate insulating layer and at least partially overlappingthe switching channel and the driving channel, respectively. The abovedisplay further comprises a second gate insulating layer at leastpartially covering the switching gate electrode and the driving gateelectrode, wherein a first thickness of the second gate insulating layerbetween the first and second storage electrodes is less than a secondthickness of the second gate insulating layer formed over the drivinggate electrode.

The above display further comprises an interlayer insulating layer atleast partially covering the data line and the driving voltage line anda passivation layer formed between the interlayer insulating layer andthe OLED, wherein the data line and the driving voltage line are formedbetween the second gate insulating layer and the interlayer insulatinglayer.

Another aspect is a method of manufacturing an organic light-emittingdiode (OLED) display, comprising forming a semiconductor layer over asubstrate, forming a first gate insulating layer over the semiconductorlayer, and forming a driving gate electrode, a switching gate electrode,and a gate connecting member over the first gate insulating layer. Themethod also comprises forming a second gate insulating layer at leastpartially covering the driving gate electrode and the switching gateelectrode and substantially simultaneously forming i) a data line,including an upper data line and a lower data line separated from eachother, ii) a first driving voltage line substantially parallel to thedata line, and iii) a second driving voltage line crossing the dataline, on the second gate insulating layer. The method further comprisesforming an interlayer insulating layer at least partially covering thedata line, the first driving voltage line, and the second drivingvoltage line. The method also comprises forming an OLED over theinterlayer insulating layer, wherein the gate connecting member isconfigured to electrically connect the upper data line to the lower dataline.

The above method further comprises forming a passivation layer afterforming the interlayer insulating layer.

The above method further comprises forming a storage capacitor where thedriving gate electrode and a portion of the first driving voltage lineoverlap.

In the above method, the driving channel has at least one curvedportion.

In the above method, the storage capacitor includes a first storageelectrode electrically connected to the driving gate electrode and asecond storage electrode electrically connected to the driving voltageline, and wherein the data line, the driving voltage line, and thesecond storage electrode are formed using the same mask.

Another aspect is an organic light-emitting diode (OLED) displaycomprising a substrate, and a data line and a driving voltage line eachformed over the substrate and configured to respectively transfer a datavoltage and a driving voltage. The display also comprises a drivingtransistor including a driving drain electrode, a driving gate electrodeelectrically connected to the driving voltage line, and a driving sourceelectrode electrically connected to the data line. The display alsocomprises a storage capacitor including a first storage electrodeelectrically connected to the driving gate electrode and a secondstorage electrode formed on the same layer and of the same material asthe driving voltage line. The display further comprises an OLEDelectrically connected to the driving drain electrode.

The above display further comprises a gate connecting member formed overthe substrate, wherein the driving voltage line includes a first drivingvoltage line substantially parallel to the data line and a seconddriving voltage line crossing the data line, wherein the data lineincludes an upper data line and a lower data line separated from theupper data line, and wherein the gate connecting member is configured toelectrically connect the upper data line to the lower data line.

The above display further comprises a semiconductor layer formed overthe substrate and including a switching channel and a driving channelseparated from each other, a first gate insulating layer at leastpartially covering the semiconductor layer, and a switching gateelectrode and a driving gate electrode formed over the first gateinsulating layer and at least partially overlapping the switchingchannel and the driving channel, respectively, wherein the gateconnecting member is formed on the same layer as the switching gateelectrode and the driving gate electrode.

The above display further comprises a second gate insulating layer atleast partially covering the switching gate electrode, the driving gateelectrode, and the gate connecting member. The above display furthercomprises an interlayer insulating layer at least partially covering thedata line and the driving voltage line and a passivation layer formedbetween the interlayer insulating layer and the OLED, wherein the dataline and the driving voltage line are formed between the second gateinsulating layer and the interlayer insulating layer.

The above display further comprises a semiconductor layer formed overthe substrate and including a switching channel and a driving channelseparated from each other. The above display further comprises a firstgate insulating layer at least partially covering the semiconductorlayer and a switching gate electrode and a driving gate electrode formedover the first gate insulating layer and at least partially overlappingthe switching channel and the driving channel, respectively. The abovedisplay further comprises a second gate insulating layer at leastpartially covering the switching gate electrode and the driving gateelectrode, wherein a first thickness of the second gate insulating layerbetween the first and second storage electrodes is less than a secondthickness of the second gate insulating layer formed over the drivinggate electrode.

According to at least one of the disclosed embodiments, the secondstorage capacitive plate is formed with the same layer and the samematerial as the driving voltage line and the data line such that atleast one mask can be eliminated.

Further, the data line is divided into the upper data line and the lowerdata line to not be short-circuited to each other in the crossingportion of the data line and the second driving voltage line of the samelayer, and the upper data line and the lower data line that areseparated are connected through the gate connecting member, therebyforming the data line and the second driving voltage line at the samelayer. Accordingly, the driving voltage line can be formed with a meshstructure by connecting the first driving voltage line of a verticaldirection and the second driving voltage line of a horizontal directionto each other such that the voltage drop of the driving voltage ELVDDcan be prevented.

In addition, the thickness of the second gate insulating layerpositioned between the first storage electrode and the second storageelectrode is thinner than the thickness of the second gate insulatinglayer on the other position such that the storage capacitance of thestorage capacitor can be maximized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an equivalent circuit diagram of one pixel of an OLED displayaccording to an exemplary embodiment.

FIG. 2 is a timing diagram of a signal applied to one pixel in the OLEDdisplay according to the exemplary embodiment of FIG. 1 .

FIG. 3 is a schematic view of a plurality of transistors and a capacitorof an OLED display according to an exemplary embodiment.

FIG. 4 is a detailed layout view of FIG. 3 .

FIG. 5 is a cross-sectional view of the OLED display of FIG. 4 takenalong a line V-V.

FIG. 6 is a cross-sectional view of the OLED display of FIG. 4 takenalong lines VI-VI and VI′-VI′.

FIG. 7 , FIG. 10 , and FIG. 13 are layout views sequentially showing amanufacturing method of an OLED display according to exemplaryembodiments.

FIG. 8 is a cross-sectional view of the OLED display of FIG. 7 takenalong a line VIII-VIII.

FIG. 9 is a cross-sectional view of the OLED display of FIG. 7 takenalong lines IX-IX and IX′-IX′.

FIG. 11 is a cross-sectional view of the OLED display of FIG. 10 takenalong a line XI-XI.

FIG. 12 is a cross-sectional view of the OLED display of FIG. 10 takenalong lines XII-XII and XII′-XII′.

FIG. 14 is a cross-sectional view of the OLED display of FIG. 13 takenalong a line XIV-XIV.

FIG. 15 is a cross-sectional view of the OLED display of FIG. 13 takenalong lines XV-XV and XV′-XV′.

FIG. 16 is a schematic view of a plurality of transistors and acapacitor of an OLED display according to another exemplary embodiment.

FIG. 17 is a detailed layout view of FIG. 16 .

FIG. 18 is a cross-sectional view of the OLED display of FIG. 17 takenalong a line XVIII-XVIII.

FIG. 19 is a cross-sectional view of the OLED display of FIG. 17 takenalong a line XIX-XIX.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

Since TFTs and capacitors are formed by patterning in every OLED pixel,and an organic light-emitting layer is formed thereon, the manufactureof OLED displays typically uses many masks. This results in increasedmanufacturing costs.

The present disclosure will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the disclosure are shown. As those skilled in the art would realize,the described embodiments can be modified in various different ways, allwithout departing from the spirit or scope of the present disclosure.

Parts irrelevant to a description are omitted to clearly illustrate thepresent disclosure, and like reference numbers designate likeconstituent elements through the specification.

In addition, the size and thickness of each configuration shown in thedrawings are arbitrarily shown for better understanding and ease ofdescription, but the present disclosure is not limited thereto.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. In the drawings, for better understandingand ease of description, the thicknesses of some layers and areas areexaggerated. It will be understood that when an element such as a layer,film, region, or substrate is referred to as being “on” another element,it can be directly on the other element or intervening elements can alsobe present.

In addition, unless explicitly described to the contrary, the word“comprise” and variations such as “comprises” or “comprising” will beunderstood to imply the inclusion of stated elements but not theexclusion of any other elements. In addition, “.about.on” is eitherpositioned on or below a portion of a target or positioned on the upperside based on a gravity direction, throughout the specification.

Further, in the specification, the word “in a plan view” means when anobject portion is viewed from above, and the word “in cross-section”means when a cross-section taken by vertically cutting an object portionis viewed from the side. In this disclosure, the term “substantially”includes the meanings of completely, almost completely or to anysignificant degree under some applications and in accordance with thoseskilled in the art. Moreover, “formed on” can also mean “formed over.”The term “connected” can include an electrical connection.

Now, an OLED display according to an exemplary embodiment will bedescribed with reference to FIG. 1 to FIG. 6 .

FIG. 1 is an equivalent circuit diagram of one pixel of an OLED displayaccording to an exemplary embodiment.

As illustrated in FIG. 1 , one pixel 1 of the OLED display includes aplurality of signal lines 151, 152, 153, 158, 171, 172, and 192, aplurality of transistors T1, T2, T3, T4, T5, T6, and T7 connected to thesignal lines, a storage capacitor Cst, and an OLED.

The transistors T1-T7 include a driving transistor T1, a switchingtransistor T2, a compensation transistor T3, an initializationtransistor T4, an operation control transistor T5, a light emissioncontrol transistor T6, and a bypass transistor T7.

The signal lines 151, 152, 153 and 158 include a scan line 151transferring a scan signal Sn, a previous scan line 152 transferring aprevious scan signal S(n−1) to the initialization transistor T4, a lightemission control line 153 transferring a light emission control signalEM to the operation control transistor T5 and the light emission controltransistor T6, and a bypass control line 158 transferring a bypasssignal BP to the bypass transistor T7. The signal lines 171, 172, and192 include a data line 171 crossing the scan line 151 and transferringa data signal Dm, a driving voltage line 172 transferring a drivingvoltage ELVDD and formed to be substantially parallel with the data line171, and an initialization voltage line 192 transferring aninitialization voltage Vint initializing the driving transistor T1.

A gate electrode G1 of the driving transistor T1 is connected to one endCst1 of the storage capacitor Cst, a source electrode S1 of the drivingtransistor T1 is connected to the driving voltage line 172 via theoperation control transistor T5, and a drain electrode D1 of the drivingtransistor T1 is electrically connected to an anode of the OLED via thelight emission control transistor T6. The driving transistor T1 receivesthe data signal Dm according to a switching operation of the switchingtransistor T2 to supply a driving current Id to the OLED.

A gate electrode G2 of the switching transistor T2 is connected to thescan line 121, a source electrode S2 of the switching transistor T2 isconnected to the data line 171, and a drain electrode D2 of theswitching transistor T2 is connected to the source electrode S1 and thedriving voltage line 172 via the operation control transistor T5. Theswitching transistor T2 is turned on according to the scan signal Snreceived through the scan line 121 to perform a switching operation oftransferring the data signal Dm transferred to the data line 171 to thesource electrode of the driving transistor T1.

A gate electrode G3 of the compensation transistor T3 is directlyconnected to the scan line 151, a source electrode S3 of thecompensation transistor T3 is connected to the drain electrode D1 and ananode of the OLED via the emission control transistor T6, and a drainelectrode D3 of the compensation transistor T3 is connected to the oneend Cst1, the drain electrode D4, and the gate electrode G1. Thecompensation transistor T3 is turned on according to the scan signal Snreceived through the scan line 151 to connect the gate electrode G1 tothe drain electrode D1 and diode-connect the driving transistor T1.

A gate electrode G4 of the initialization transistor T4 is connected tothe previous scan line 152, a source electrode S4 of the initializationtransistor T4 is connected to the initialization voltage line 192, and adrain electrode D4 of the initialization transistor T4 is connected tothe one end Cst1 and the gate electrode G1 through the drain electrodeD3. The initialization transistor T4 is turned on according to theprevious scan signal S(n−1) received through the previous scan line 152to transfer the initialization voltage Vint to the gate electrode G1 toperform an initialization operation of initializing a voltage of thegate electrode G1.

A gate electrode G5 of the operation control transistor T5 is connectedto the light emission control line 153, a source electrode S5 of theoperation control transistor T5 is connected to the driving voltage line172, and a drain electrode D5 of the operation control transistor T5 isconnected to the source electrode Si and the drain electrode S2.

A gate electrode G6 of the emission control transistor T6 is connectedto the light emission control line 153, the source electrode S6 isconnected to the drain electrode D1 and the source electrode S3, and thedrain electrode D6 is electrically connected to the anode of the OLED.The operation control transistor T5 and the first emission controltransistor T6 are substantially simultaneously turned on according tothe emission control signal EM transmitted to the emission control line153 such that the driving voltage ELVDD is compensated through thediode-connected driving transistor T1 and is transmitted to the OLED.

A gate electrode G7 of the thin film bypass transistor T7 is connectedto the bypass control line 158, a source electrode S7 of the bypass TFTT7 is connected to the drain electrode D6 and the anode of the OLEDtogether, and a drain electrode D7 of the bypass TFT T7 is connected tothe initialization voltage line 192 and the source electrode S4.

The other end Cst2 of the storage capacitor Cst is connected to thedriving voltage line 172, and a cathode of the OLED is connected to acommon voltage line 741 transferring a common voltage ELVSS.

Hereinafter, a detailed operation process of one pixel of the pixel unitof the OLED display according to an exemplary embodiment will bedescribed in detail with reference to FIG. 2 .

As shown in FIG. 2 , first, for an initializing period, the previousscan signal S(n−1) having a low level is supplied through the previousscan line 152. Then, the initializing TFT T4 is turned on in response tothe previous scan signal S(n−1) having the low level, the initialvoltage Vint is connected to the gate electrode G1 from theinitialization voltage line 194 through the initializing TFT T4, andthen the driving TFT T1 is initialized by the initialization voltageVint.

Thereafter, for a data programming period, the scan signal Sn having alow level is supplied through the scan line 151. Then, the switching TFTT2 and the compensating TFT T3 are turned on in response to the scansignal Sn having the low level. At this time, the driving transistor T1is diode-connected through the turned-on compensation transistor T3 andis forward biased.

Then, a compensation voltage Dm+Vth (Vth is a negative (−) value)reduced by a threshold voltage Vth of the driving TFT T1 from a datasignal Dm supplied from the data line 171 is applied to the gateelectrode G1. The driving voltage ELVDD and the compensation voltage(Dm+Vth) are applied to both terminals of the storage capacitor Cst, anda charge corresponding to a voltage difference between both terminals isstored in the storage capacitor Cst.

Next, during the emission period, the emission control signal EMsupplied from the emission control line 153 is changed from the highlevel into the low level. Thus, the operation control transistor T5 andthe emission control transistor T6 are turned on by the emission controlsignal EM of the low level during the emission period.

Thus, a driving current Id is generated according to the voltagedifference between the gate voltage of the gate electrode G1 and thedriving voltage ELVDD, and the driving current Id is supplied to theOLED through the emission control transistor T6. The gate-source voltageVgs of the driving TFT T1 is maintained as “(Dm+Vth)-ELVDD” by thestorage capacitor Cst for the emission period, and according to acurrent-voltage relationship of the driving TFT T1, the driving current1 d is proportional to the square “(Dm-ELVDD).sup.2” of a value obtainedby subtracting the threshold voltage from the source-gate voltage.Accordingly, the driving current 1 d is determined regardless of thethreshold voltage Vth of the driving TFT T1.

In this case, the bypass transistor T7 is transmitted with the bypasssignal BP from the bypass control line 158. Thus, a portion of thedriving current Id is discharged as the bypass current Ibp through thebypass transistor T7.

When a minimum current of the driving transistor T1 displaying the blackimage flows as the driving current, if the OLED is also emitted, theblack image is not normally displayed. Accordingly, the bypasstransistor T7 of the OLED display according to an exemplary embodimentcan disperse the portion of the minimum current of the drivingtransistor T1 as the bypass current Ibp through the other current pathbesides the current path of the OLED side. Here, the minimum current ofthe driving transistor T1 corresponds to the current in a condition whenthe driving transistor T1 is turned off and the gate-source voltage Vgsof the driving transistor T1 is less than the threshold voltage Vth. Theminimum driving current (for example, a current of about 10 pA or less)under the condition in which the driving transistor T1 is turned off istransferred to the OLED to be expressed as an image with blackluminance. When the minimum driving current expressing the black imageflows, an influence on a bypass transfer of the bypass current Ibp islarge, but when a large driving current expressing an image such as anormal image or a white image flows, there can be little influence onthe bypass current Ibp. Accordingly, when the driving current displayinga black image flows, the light emission current Iholed of the OLED has aminimum current amount that can express the black image. Therefore, ablack luminance image is implemented by using the bypass transistor T7,thereby improving a contrast ratio. In FIG. 2 , the bypass signal BP isthe same as a next scan signal S(n+1), but is not necessarily limitedthereto. Also, in an exemplary embodiment, the structure of the seventransistors including the bypass transistor T7 and one capacitor isshown, however the described technology is not limited thereto.

Next, the detailed structure of the pixel of the OLED display shown inFIG. 1 will be described with reference to FIG. 3 to FIG. 6 as well asFIG. 1 .

FIG. 3 is a schematic view of a plurality of transistor and a capacitorof an OLED display according to an exemplary embodiment. FIG. 4 is adetailed layout view of FIG. 3 . FIG. 5 is a cross-sectional view of theOLED display of FIG. 4 taken along a line V-V. FIG. 6 is across-sectional view of the OLED display of FIG. 4 taken along linesVI-VI and VI′-VI′.

Hereinafter, a detailed planar structure of the OLED display accordingto the exemplary embodiment will be first described in detail withreference to FIG. 3 and FIG. 4 , and a detailed cross-sectionalstructure will be described in detail with reference to FIG. 5 and FIG.6 .

Firstly, as shown in FIG. 3 , the OLED display includes a scan line 151,a previous scan line 152, a light emission control line 153, and abypass control line 158 respectively applying a scan signal Sn, aprevious scan signal S(n−1), a light emission control signal EM, and abypass signal BP. The lines 151, 152, 153, and 158 are formed in the rowdirection. The OLED display also includes a data line 171 and a drivingvoltage line 172 crossing the scan line 151, the previous scan line 152,the light emission control line 153, and the bypass control line 158.The driving voltage line 172 also applies a data signal Dm and a drivingvoltage ELVDD to the pixel. The initialization voltage Vint istransmitted to the compensation transistor T3 through the initializationvoltage line 192. The driving voltage line 172 includes a first drivingvoltage line 172 a substantially parallel to the data line 171 and asecond driving voltage line 172 b substantially parallel to the scanline 151. The first driving voltage line 172 a and the second drivingvoltage line 172 b are electrically connected to each other.

Also, the pixel 1 includes the driving transistor T1, the switchingtransistor T2, the compensation transistor T3, the initializationtransistor T4, the operation control transistor T5, the first emissioncontrol transistor T6, the second emission control transistor T7, thestorage capacitor Cst, and the OLED. The OLED includes a pixel electrode191, an organic emission layer 370, and a common electrode 270. In thiscase, the compensation transistor T3 and the initialization transistorT4 are formed as dual gate transistors to prevent a leakage current.

Each channel of the transistors T1-T7 is formed in one semiconductor orsemiconductor layer 130 connected thereto, and the semiconductor 130 canbe curved with various shapes. The semiconductor 130 can be formed of apolycrystalline semiconductor material or an oxide semiconductormaterial. The oxide semiconductor can include one of oxides based ontitanium (Ti), hafnium (Hf), zirconium (Zr), aluminum (Al), tantalum(Ta), germanium (Ge), zinc (Zn), gallium (Ga), tin (Sn), or indium (In),zinc oxide (ZnO), indium-gallium-zinc oxide (InGaZnO4), indium zincoxide (Zn—In—O), zinc-tin oxide (Zn—Sn—O), indium-gallium oxide(In—Ga—O), indium-tin oxide (In—Sn—O), indium-zirconium oxide (In—Zr—O),indium-zirconium-zinc oxide (In—Zr—Zn—O), indium-zirconium-tin oxide(In—Zr—Sn—O), indium-zirconium-gallium oxide (In—Zr—Ga—O),indium-aluminum oxide (In—Al—O), indium-zinc-aluminum oxide(In—Zn—Al—O), indium-tin-aluminum oxide (In—Sn—Al—O),indium-aluminum-gallium oxide (In—Al—Ga—O), indium-tantalum oxide(In—Ta—O), indium-tantalum-zinc oxide (In—Ta—Zn—O), indium-tantalum-tinoxide (In—Ta—Sn—O), indium-tantalum-gallium oxide (In—Ta—Ga—O),indium-germanium oxide (In—Ge—O), indium-germanium-zinc oxide(In—Ge—Zn—O), indium-germanium-tin oxide (In—Ge—Sn—O), indium-germaniumgallium oxide (In—Ge—Ga—O), titanium-indium-zinc oxide (Ti—In—Zn—O), andhafnium-indium-zinc oxide (Hf—In—Zn—O), which are complex oxidesthereof. In the case when the semiconductor layer 130 is formed of theoxide semiconductor, in order to protect the oxide semiconductor that isvulnerable to an external environment such as a high temperature, aseparate passivation layer can be added.

The semiconductor layer 130 can include a channel region in which achannel is doped with an N-type impurity or a P-type impurity, and asource region and a drain region which are formed at respective sides ofthe channel region. The source and drain regions are formed by doping animpurity which is opposite in polarity to the impurity doped in thechannel region. In the present exemplary embodiment, the source dopingregion and the drain doping region respectively correspond to the sourceelectrode and the drain electrode. The source electrode and the drainelectrode can be formed by only doping the corresponding regions. Also,in the semiconductor 130, the region between the source electrodes andthe drain electrodes of the different transistors are also doped suchthat the source electrode and the drain electrode are electricallyconnected to each other.

As shown in FIG. 4 , a channel 131 includes a driving channel 131 aformed in the driving transistor T1, a switching channel 131 b formed inthe switching transistor T2, a compensation channel 131 c formed in thecompensation transistor T3, an initialization channel 131 d formed inthe initialization transistor T4, an operation control channel 131 eformed in the operation control transistor T5, a light emission controlchannel 131 f formed in the first emission control transistor T6, and abypass channel 131 g formed in the second emission control transistorT7.

The driving transistor T1 includes the driving channel 131 a, a drivinggate electrode 155 a, a driving source electrode 136 a, and a drivingdrain electrode 137 a. The driving channel 131 a is curved and can havea meandering shape or a zigzag shape. As such, the curved drivingchannel 131 a is formed, and thus the driving channel 131 a can beelongated in a narrow space. Accordingly, since the driving channel 131a can be elongated, a driving range of the gate voltage applied to thedriving gate electrode 155 a is increased. Accordingly, since thedriving range of a gate voltage is increased, an intensity of lightemitted from the OLED can be more finely controlled by changing amagnitude of the gate voltage, thereby enhancing resolution of the OLEDdisplay and improving display quality. The shape of such a drivingchannel 131 a is variously modified, and thus various exemplaryembodiments such as ‘reverse S’, ‘S’, ‘M’, ‘W’, and the like arepossible.

The driving gate electrode 155 a overlaps the driving channel 131 a, andthe driving source electrode 136 a and the driving drain electrode 137 aare formed to be adjacent to respective sides of the driving channel 131a. The driving gate electrode 155 a is connected to a first dataconnecting member 174 through a contact hole 61.

The switching transistor T2 includes the switching channel 131 b, aswitching gate electrode 155 b, a switching source electrode 136 b, anda switching drain electrode 137 b. The switching gate electrode 155 b isa part extending downwardly from the scan line 151 and overlaps theswitching channel 131 b, and the switching source electrode 136 b andthe switching drain electrode 137 b are formed to be adjacent torespective sides of the switching channel 131 b. The switching sourceelectrode 136 b is connected to the data line 171 through a contact hole62.

The compensation transistor T3 includes the compensation channel 131 c,a compensation gate electrode 155 c, a compensation source electrode 136c, and a compensation drain electrode 137 c. The compensation gateelectrode 155 c that is a part of the scan line 151 is formed to preventa leakage current and overlaps the compensation channel 131 c. Thecompensation source electrode 136 c and the compensation drain electrode137 c are formed to be adjacent to respective sides of the compensationchannel 131 c. The compensation drain electrode 137 c is connected to afirst data connecting member 174 through a contact hole 63.

The initialization transistor T4 includes the initialization channel 131d, an initialization gate electrode 155 d, an initialization sourceelectrode 136 d, and an initialization drain electrode 137 d. Theinitialization gate electrode 155 d that is a part of the previous scanline 152 is formed as two to prevent the leakage current and overlapsthe initialization channel 131 d. The initialization source electrode136 d and the initialization drain electrode 137 d are formed to beadjacent to respective sides of the initialization channel 131 d. Theinitialization source electrode 136 d is connected to a second dataconnecting member 175 through a contact hole 64.

The operation control transistor T5 includes the operation controlchannel 131 e, an operation control gate electrode 155 e, an operationcontrol source electrode 136 e, and an operation control drain electrode137 e. The operation control gate electrode 155 e that is a part of thelight emission control line 153 overlaps the operation control channel131 e. The operation control source electrode 136 e and the operationcontrol drain electrode 137 e are formed to be adjacent to respectivesides of the operation control channel 131 e. The operation controlsource electrode 136 e is connected to a part that extends from thedriving voltage line 172 through a contact hole 65.

The light emission control transistor T6 includes the light emissioncontrol channel 131 f, a light emission control gate electrode 155 f, alight emission control source electrode 136 f, and a light emissioncontrol drain electrode 137 f. The light emission control gate electrode155 f that is a part of the light emission control line 153 overlaps thelight emission control channel 131 f. The light emission control sourceelectrode 136 f and the light emission control drain electrode 137 f areformed to be adjacent to respective sides of the light emission controlchannel 131 f. The light emission control drain electrode 137 f isconnected to the third data connecting member 179 through a contact hole66.

The bypass transistor T7 includes the bypass channel 131 g, a bypassgate electrode 155 g, a bypass source electrode 136 g, and a bypassdrain electrode 137 g. The bypass gate electrode 155 g that is a part ofthe bypass control line 158 overlaps the bypass channel 131 g, and thebypass source electrode 136 g and the bypass drain electrode 137 g areformed to be adjacent to respective sides of the bypass channel 131 g.

The bypass source electrode 136 g is connected directly to the lightemission control drain electrode 137 f, and the bypass drain electrode137 g is connected directly to the initialization source electrode 136d.

One end of the driving channel 131 a is connected to the switching drainelectrode 137 b and the operation control drain electrode 137 e. Theother end of the driving channel 131 a is connected to the compensationsource electrode 136 c and the light emission control source electrode136 f.

The storage capacitor Cst includes a first storage electrode 155 a and asecond storage electrode 178 formed via a second gate insulating layer142 interposed therebetween. The first storage electrode 155 acorresponds to the driving gate electrode 155 a. The second storageelectrode 178 is an expansion region of the first driving voltage line172 a and is formed one by one for each pixel. Here, the gate insulatinglayer 142 acts as the dielectric of the storage capacitor Cst, and astorage capacitance is determined by a charge charged to the storagecapacitor Cst and a voltage between the electrodes 155 a and 178. Asdescribed above, by using the driving gate electrode 155 a as the firststorage electrode 155 a, a space for forming the storage capacitor canbe obtained in the space that is decreased by the driving channel 131 aoccupied with the large area in the pixel.

The first storage electrode 155 a is connected to the first dataconnecting member 174 through the contact hole 61 formed in the secondgate insulating layer 142. The first data connecting member 174 isformed to be parallel to and on the same layer as the data line 171. Thedriving gate electrode 155 a and the compensation drain electrode 137 care connected to each other.

Accordingly, the storage capacitor Cst stores a storage capacitancecorresponding to the difference between the driving voltage ELVDDtransferred to the second storage electrode 178 through the drivingvoltage line 172 a and the gate voltage of the driving gate electrode155 a.

In this case, the second driving voltage line 172 b connects the firstdriving voltage lines 172 a formed in the pixels adjacent to each other.The second driving voltage line 172 b and the data line 171 are formedon the same layer, thereby overlapping each other. Accordingly, toprevent the short of the second driving voltage line 172 b and the dataline 171, the data line 171 is divided into an upper data line 171 a anda lower data line 171 b in the portion crossing the second drivingvoltage line 172 b. One end of the upper data line 171 a is connected toa gate connecting member 159 through a contact hole 67, and one end ofthe lower data line 171 b facing the upper data line 171 a is connectedto the gate connecting member 159 through a contact hole 68. The gateconnecting member 159 is formed of the same material and on the samelayer as the scan line 121.

A third data connecting member 179 is connected to the pixel electrode191 through a contact hole 81, and the second data connecting member 175is connected to the initialization voltage line 192 through a contacthole 82.

Hereinafter, a structure of the OLED display according to exemplaryembodiments will be described in detail with reference to FIG. 5 andFIG. 6 .

In this case, since the operation control TFT T5 is almost the same as alaminating structure of the emission control TFT T6, a detaileddescription is omitted.

A buffer layer 120 is formed on a substrate 110. The substrate 110 canbe formed of an insulating substrate such as glass, quartz, ceramic, andplastic, and the buffer layer 120 blocks an impurity from the substrate110 in a crystallization process to form a polycrystallinesemiconductor, thereby improving a characteristic of the polycrystallinesemiconductor and reducing a stress applied to the substrate 110.

The semiconductor 130 including the driving channel 131 a, the switchingchannel 131 b, the compensation channel 131 c, the initializationchannel 131 d, the operation control channel 131 e, the light emissioncontrol channel 131 f, and the bypass channel 131 g is formed on thebuffer layer 120. Among the semiconductor 130, the driving sourceelectrode 136 a and the driving drain electrode 137 a are formed atrespective sides of the driving channel 131 a, the switching sourceelectrode 136 b and the switching drain electrode 137 b are formed atrespective sides of the switching channel 131 b, and the compensationsource electrode 136 c and the compensation drain electrode 137 c areformed at respective sides of the compensation channel 131 c. Also, theinitialization source electrode 136 d and the initialization drainelectrode 137 d are formed at respective sides of the initializationchannel 131 d, the operation control source electrode 136 e and theoperation control drain electrode 137 e are formed at respective sidesof the operation control channel 131 e, the light emission controlsource electrode 136 f and the light emission control drain electrode137 f are formed at respective sides of the light emission controlchannel 131 f, and the bypass source electrode 136 g and the bypassdrain electrode 137 g are formed at respective sides of the bypasschannel 131 g.

A first gate insulating layer 141 covering the semiconductor 130 isformed thereon. On the first gate insulating layer 141, gate wires 151,152, 153, 155 a, 155 b, 155 c, 155 d, 155 e, 155 f, 158, and 159including the scan line 151 including the switching gate electrode 155 band the compensation gate electrode 155 c, the previous scan line 152including the initialization gate electrode 155 d, the light emissioncontrol line 153 including the operation control gate electrode 155 eand the light emission control gate electrode 155 f, the driving gateelectrode (the first storage electrode) 155 a, the bypass control line158, and the gate connecting member 159 are formed.

The second gate insulating layer 142 is formed on the gate wires 151,152, 153, 155 a, 155 b, 155 c, 155 d, 155 e, 155 f, 158, and 159 and thefirst gate insulating layer 141. The first gate insulating layer 141 andthe second gate insulating layer 142 are formed of a silicon nitride(SiNx) or a silicon oxide (SiOx).

On the second gate insulating layer 142, data wires 171, 172 a, 172 b,174, 175, 178, and 179 including the data line 171, the first drivingvoltage line 172 a including the second storage electrode 178 and thesecond driving voltage line 172 b, the first data connecting member 174,the second data connecting member 175, and the third data connectingmember 179 are formed.

The data wires 171, 172 a, 172 b, 174, 175, 178, and 179 can be formedof a triple layer of titanium/aluminum/titanium (Ti/Al/Ti), and sincealuminum is a low resistance metal, a voltage drop is prevented.

As described above, the second storage electrode 178 is formed of thesame material and on the same layer as the second driving voltage line172 b and the data line 171 without the formation of the second storagecapacitive plate as a separate layer such that a number of masks used inmanufacturing can be reduced. Also, the second storage electrode 178,the second driving voltage line 172 b, and the data line 171 are formedon the same layer such that an insulating layer to insulate the secondstorage electrode 178 from the second driving voltage line 172 b and thedata line 171 is not necessary and the short between the second storageelectrode 178 and the second driving voltage line 172 b and the dataline 171 can be prevented.

The data line 171 is connected to the switching source electrode 136 bthrough the contact hole 62 formed in the first and second gateinsulating layers 141 and 142. The second data connecting member 175 isconnected to the initialization drain electrode 137 d through thecontact hole 64 formed in the first and second gate insulating layers141 and 142. The third data connecting member 179 is connected to thelight emission control drain electrode 137 f through the contact hole 66formed in the first and second gate insulating layers 141 and 142. Also,one end of the upper data line 171 a is connected to one end of the gateconnecting member 159 through the contact hole 67 formed in the firstand second gate insulating layers 141 and 142, and one end of the lowerdata line 171 b separated from the upper data line 171 a is connected tothe other end of the gate connecting member 159 through the contact hole68.

An interlayer insulating layer 160 covering the data wires 171, 172 a,172 b, 174, 175, 178, and 179 and the second gate insulating layer 142is formed thereon. The interlayer insulating layer 160 is formed of asilicon nitride (SiNx) or a silicon oxide (SiOx). As described above,the data wire is covered by the interlayer insulating layer 160 suchthat the data wire can be protected from external moisture. Apassivation layer 180 covering the interlayer insulating layer 160 isformed thereon. The passivation layer 180 can be formed of an organiclayer. A pixel electrode 191 and an initialization voltage line 192 areformed on the passivation layer 180. The third data connecting member179 is connected to the pixel electrode 191 through the contact hole 81formed in the passivation layer 180, and the second data connectingmember 175 is connected to the initialization voltage line 192 throughthe contact hole 82 of the passivation layer 180.

As described above, the data line 171 is divided into the upper dataline 171 a and the lower data line 171 b in the crossing portion wherethe data line 171 and the second driving voltage line 172 b cross. Thedivided upper data line 171 a and lower data line 171 b are connectedthrough the gate connecting member 159 such that the data line 171 andthe second driving voltage line 172 b can be formed on the same layerwithout the generation of the short-circuit therebetween. Accordingly,the driving voltage line 172 can be formed of a mesh structure in whichthe first driving voltage line 172 a of the vertical direction and thesecond driving voltage line 172 b of the horizontal direction areconnected to each other, thereby preventing the voltage drop of thedriving voltage ELVDD.

A pixel definition layer 350 covering the passivation layer 180, theinitialization voltage line 192, and the edge of the pixel electrode 191is formed thereon. The pixel definition layer 350 has a pixel opening351 exposing the pixel electrode 191. The pixel defining layer 190 canbe formed of a polyacrylate resin, a polyimide resin, or a silica-basedinorganic material.

The organic emission layer 370 is formed on the pixel electrode 191exposed by the pixel opening 351, and the common electrode 270 is formedon the organic emission layer 370. As described above, the OLEDincluding the pixel electrode 191, the organic emission layer 370, andthe common electrode 270 is formed.

Herein, the pixel electrode 191 is an anode which is a hole injectionelectrode, and the common electrode 270 is a cathode which is anelectron injection electrode. However, the exemplary embodiments are notlimited thereto, and the pixel electrode 191 can be the cathode and thecommon electrode 270 can be the anode according to a driving method ofthe OLED display. When holes and electrons are injected into the organicemission layer 370 from the pixel electrode 191 and the common electrode270, respectively, and excitons acquired by combining the injected holesand electrons fall from an excitation state to a ground state, light isemitted.

The organic emission layer 370 is formed of a low-molecular organicmaterial or a high-molecular organic material such aspoly(3,4-ethylenedioxythiophene) (PEDOT). Further, the organic emissionlayer 370 can be formed of multiple layers including at least one of anemission layer, a hole injection layer (HIL), a hole transporting layer(HTL), an electron transporting layer (ETL), and an electron injectionlayer (EIL). When the organic emission layer 370 includes all of thelayers, the hole injection layer is formed on the pixel electrode 191which is the positive electrode, and the hole transporting layer, theemission layer, the electron transporting layer, and the electroninjection layer are sequentially laminated thereon.

The organic emission layer 370 can include a red organic emission layeremitting red light, a green organic emission layer emitting green light,and a blue organic emission layer emitting blue light. The red, green,and blue organic emission layers are formed at a red pixel, a greenpixel, and a blue pixel, respectively, to implement color images.

Further, in the organic emission layer 370, all of the red, green, andblue organic emission layers are laminated together on the red pixel,the green pixel, and the blue pixel. A red color filter, a green colorfilter, and a blue color filter are formed for each pixel to implementthe color images. As another example, a white organic emission layeremitting white light is formed on all of the red, green, and bluepixels, and the red, green, and blue color filters are formed for eachpixel to implement the color images. In some embodiments, when the colorimages are implemented by using the white organic emission layer and thecolor filters, a deposition mask for depositing the red, green, and blueorganic emission layers on individual pixels, that is, the red pixel,the green pixel, and the blue pixel, respectively, are not used.

The white organic emission layer described in another example can beformed by one organic emission layer, and even includes a configurationthat can emit white light by laminating a plurality of organic emissionlayers. As an example, the white organic emission layer can include aconfiguration that enables the white light to be emitted by combining atleast one yellow organic emission layer and at least one blue organicemission layer, a configuration that enables the white light to beemitted by combining at least one cyan organic emission layer and atleast one red organic emission layer, a configuration that enables thewhite light to be emitted by combining at least one magenta organicemission layer and at least one green organic emission layer, and thelike.

An encapsulation member (not shown) protecting the OLED can be formed onthe common electrode 270. And the encapsulation member can be sealed bya sealant and can be formed of various materials such as glass, quartz,ceramic, plastic, and a metal. On the other hand, a thin filmencapsulation layer can be formed on the common electrode 270 bydepositing the inorganic layer and the organic layer with the usage ofthe sealant.

A manufacturing method of the OLED display according to an exemplaryembodiment will now be described with reference to accompanyingdrawings.

FIG. 7 , FIG. 10 , and FIG. 13 are layout views sequentially showing amanufacturing method of an OLED display according to an exemplaryembodiment. FIG. 8 is a cross-sectional view of the OLED display of FIG.7 taken along a line VIII-VIII. FIG. 9 is a cross-sectional view of theOLED display of FIG. 7 taken along lines IX-IX and IX′-IX′. FIG. 11 is across-sectional view of the OLED display of FIG. 10 taken along a lineXI-XI. FIG. 12 is a cross-sectional view of the OLED display of FIG. 10taken along lines XII-XII and XII′-XII′. FIG. 14 is a cross-sectionalview of the OLED display of FIG. 13 taken along a line XIV-XIV. FIG. 15is a cross-sectional view of the OLED display of FIG. 13 taken alonglines XV-XV and XV′-XV′.

First, as illustrated in FIG. 7 to FIG. 9 , the buffer layer 120 isformed on the substrate 110. The buffer layer 120 can be formed of asingle layer of a silicon nitride or a laminate layer of a siliconnitride and a silicon oxide, and is deposited on an entire surface ofthe substrate 110 by a method such as plasma enhanced chemical vapordeposition (PECVD). In addition, the semiconductor layer is formed onthe buffer layer 120. The semiconductor layer can be formed ofpolysilicon or an oxide semiconductor, and the polysilicon can be formedby a method of forming an amorphous silicon layer and then crystallizingthe layer. Various known methods can be applied as the crystallizingmethod, and for example, the amorphous silicon layer can be crystallizedby using heat, a laser, Joule heat, an electric field, a catalyst metal,or the like. The semiconductor layer is an intrinsic semiconductor thatis not doped with the impurity. In addition, on the polycrystallinesemiconductor layer, a photolithography process is performed by using afirst mask, and the polycrystalline semiconductor layer is patterned asthe semiconductor 130 having the shape illustrated in FIG. 7 . Thesemiconductor 130 is not doped, and as a result, the semiconductor 131is not divided into the semiconductor, the source electrode, and thedrain electrode configuring each transistor. Also, the channel dopinghaving a low doping concentration is performed to the semiconductor 130to make the semiconductor 130 into an impurity semiconductor.

Next, as shown in FIG. 10 to FIG. 12 , the first gate insulating layer141 covering the buffer layer 120 and the semiconductor 130 is formedthereon. The first gate insulating layer 141 is formed by entirelydepositing a silicon nitride (SiNx) or a silicon oxide (SiOx) by amethod such as plasma enhanced chemical vapor deposition (PECVD).Further, a gate metal layer is deposited on the first gate insulatinglayer 141. The gate metal layer is patterned through a photolithographyprocess by using a second mask. As a result, the gate wire including thescan line 151, the previous scan line 152, the light emission controlline 153, the bypass control line 158, the driving gate electrode 155 a,and the gate connecting member 159 is formed. The gate metal layer canbe formed as a multilayer in which a metal layer formed of any one ofcopper (Cu), a copper alloy, aluminum (Al), and an aluminum alloy and ametal layer including any one of molybdenum (Mo) and a molybdenum alloyare laminated.

Source and drain doping of a higher doping concentration than thechannel doping is performed to the semiconductor 130. The semiconductor130 is source/drain-doped to the exposed region except for the portionthat is covered by the switching gate electrode 155 b, the compensationgate electrode 155 c, the initialization gate electrode 155 d, theoperation control gate electrode 155 e, the light emission control gateelectrode 155 f, the bypass gate electrode 155 g, and the driving gateelectrode 155 a. As a result, the source electrode and the drainelectrode of each transistor are formed. The channel 131 of eachtransistor is formed in the region that is covered to not be doped inthe semiconductor 130. That is, the driving channel 131 a, the switchingchannel 131 b, the compensation channel 131 c, the initializationchannel 131 d, the operation control channel 131 e, the light emissioncontrol channel 131 f, and the bypass channel 131 g are substantiallysimultaneously formed. As described above, a separate mask is notrequired when source/drain-doping the semiconductor 130.

Next, as shown in FIG. 13 to FIG. 15 , the second gate insulating layer142 covering the first gate insulating layer 141, the scan line 151, theprevious scan line 152, the light emission control line 153, the bypasscontrol line 158, and the driving gate electrode 155 a is formedthereon. The first insulating layer 141 is formed by entirely depositinga silicon nitride (SiNx) or a silicon oxide (SiOx) by a method such asplasma enhanced chemical vapor deposition (PECVD). In addition, theimpurity doped on the semiconductor 130 is positioned well by performinga dopant activation process, and the damage to an interface between thesemiconductor 130 and the first insulating layer 141 is eliminated.

The first gate insulating layer 141 and the second gate insulating layer142 are patterned by the photolithography process using a third mask toform a plurality of contact holes 61, 62, 63, 64, 65, 66, 67, and 68. Adata metal layer is formed on the second gate insulating layer 142. Thedata metal layer can be formed as a multilayer in which a metal layerformed of any one of copper (Cu), a copper alloy, aluminum (Al), and analuminum alloy and a metal layer formed of molybdenum (Mo) and amolybdenum alloy are laminated. For example, the data metal layer can beformed as a triple layer of titanium/aluminum/titanium (Ti/Al/Ti), atriple layer of molybdenum/aluminum/molybdenum (Mo/Al/Mo), or a triplelayer of molybdenum/copper/molybdenum (Mo/Cu/Mo).

In addition, the data metal layer is patterned by the photolithographyprocess using a fourth mask. Accordingly, the data wires including theupper data line 171 a, the lower data line 171 b, the first drivingvoltage line 172 a including the second storage electrode 178, thesecond driving voltage line 172 b, the first data connecting member 174,the second data connecting member 175, and the third data connectingmember 179 is formed on the second gate insulating layer 142. Asdescribed above, the second storage electrode 178 is formed of the samematerial and on the same layer as the second driving voltage line 172 band the data line 171 without the formation of the second storagecapacitive plate as the separate layer, thereby reducing the number ofmasks used in the manufacturing. Also, by connecting the upper data line171 a and the lower data line 171 b that are separated through the gateconnecting member 159, the data line 171 and the second driving voltageline 172 b can be formed with the same layer.

Next, as shown in FIG. 4 to FIG. 6 , the interlayer insulating layer 160covering the data wires 171, 172, 174, 175, 178, and 179 is formed onthe second gate insulating layer 142. Also, a passivation layer 180 isformed on the interlayer insulating layer 160. The interlayer insulatinglayer 160 and the passivation layer 180 are patterned by thephotolithography process using the fifth mask to form the contact holes81 and 82. Further, a pixel electrode layer is formed on the passivationlayer 180 and is patterned by the photolithography process using a sixthmask. Accordingly, the pixel electrode 191 connected to the third dataconnecting member 179 through the contact hole 81 and the initializationvoltage line 192 connected to the second data connecting member 175through the contact hole 82 are formed on the passivation layer 180. Thepixel definition layer 350 covering the pixel electrode 191 and theinitialization voltage line 192 is formed on the passivation layer 180and is patterned to form the pixel opening 351 exposing the portion ofthe pixel electrode 191 by using a seventh mask. The organic emissionlayer 370 is formed on the pixel electrode 191 exposed through the pixelopening 351 of the pixel definition layer 350. The common electrode 270is formed on the organic emission layer 370 to complete the OLED. Thecommon electrode 270 is formed throughout the entire region on the pixeldefinition layer 350 such that the separate mask is not used. Asdescribed, the manufacturing method from the semiconductor 130 to thecommon electrode 270 using the total of seven masks is referred to as a7 mask process, and the structure of the OLED display manufactured bythe 7 mask process is referred to as a 7 mask structure.

On the other hand, in the present exemplary embodiment, the 7 maskstructure in which the storage capacitor and the driving gate electrodeoverlap is described, however another exemplary embodiment of the 7 maskstructure in which the storage capacitor and the driving gate electrodedo not overlap is possible.

Next, another exemplary embodiment will be described with reference toFIG. 16 to FIG. 19 .

FIG. 16 is a schematic view of a plurality of transistor and a capacitorof an OLED display according to another exemplary embodiment. FIG. 17 isa detailed layout view of FIG. 16 . FIG. 18 is a cross-sectional view ofthe OLED display of FIG. 17 taken along a line XVIII-XVIII. FIG. 19 is across-sectional view of the OLED display of FIG. 17 taken along a lineXIX-XIX.

The exemplary embodiment shown in FIG. 16 to FIG. 19 is substantiallythe same as the exemplary embodiment shown in FIG. 1 to FIG. 6 exceptfor that the storage capacitor and the driving gate electrode thatoverlap each other such that the repeated description is omitted.

As shown in FIG. 16 to FIG. 19 , the OLED display according to thecurrent exemplary embodiment includes the scan line 151, the previousscan line 152, the light emission control line 153, and the bypasscontrol line 158, and the data line 171. The OLED display also includesthe driving voltage line 172 crossing the scan line 151, the previousscan line 152, the light emission control line 153, and the bypasscontrol line 158. Also, the driving transistor T1, the switchingtransistor T2, the compensation transistor T3, the initializationtransistor T4, the operation control transistor T5, the light emissioncontrol transistor T6, the bypass transistor T7, the storage capacitorCst, and the OLED(OLED) are formed in the pixel 1. The OLED includes thepixel electrode 191, the organic emission layer 370, and the commonelectrode 270.

The channel 131 includes a driving channel 131 a formed in the drivingtransistor T1, a switching channel 131 b formed in the switchingtransistor T2, a compensation channel 131 c formed in the compensationtransistor T3, and an initialization channel 131 d formed in theinitialization transistor T4. The channel 131 also includes an operationcontrol channel 131 e formed in the operation control transistor T5, alight emission control channel 131 f formed in the first emissioncontrol transistor T6, and a bypass channel 131 g formed in the secondemission control transistor T7.

The storage capacitor Cst includes a first storage electrode 157 and thesecond storage electrode 178 formed via the second gate insulating layer142 interposed therebetween. The first storage electrode 157 isseparated from the driving gate electrode 155 a and is formed on thesame layer. The second storage electrode 178 is the expansion region ofthe first driving voltage line 172 a and is formed one by one for eachpixel.

The first storage electrode 157 is connected to a lower portion of thefirst data connecting member 174 through the contact hole 67, and thefirst data connecting member 174 is connected to the driving gateelectrode 155 a through the contact hole 61. Accordingly, the firststorage electrode 157 is electrically connected to the driving gateelectrode 155 a.

Accordingly, the storage capacitor Cst stores the storage capacitancecorresponding to the difference between the driving voltage ELVDDtransmitted to the second storage electrode 178 through the drivingvoltage line 172 and the gate voltage Vg of the driving gate electrode155 a.

The first data connecting member 174 is formed to be substantiallyparallel to the data line 171. An upper portion of the first dataconnecting member 174 is connected to the initialization drain electrode137 d through the contact hole 63, a center portion of the first dataconnecting member 174 is connected to the driving gate electrode 155 athrough the contact hole 61, and a lower portion of the first dataconnecting member 174 is connected to the first storage electrode 157through the contact hole 67.

Next, a cross-sectional structure of the OLED display according to thesecond exemplary embodiment will be described with reference to FIG. 18and FIG. 19 .

The buffer layer 120 is formed on the substrate 110. The semiconductor130 including the driving channel 131 a, the switching channel 131 b,the compensation channel 131 c, the initialization channel 131 d, theoperation control channel 131 e, the light emission control channel 131f, and the bypass channel 131 g is formed on the buffer layer 120.

The first gate insulating layer 141 covering the semiconductor 130 isformed thereon. The scan line 151 including the switching gate electrode155 b and the compensation gate electrode 155 c, the previous scan line152 including the initialization gate electrode 155 d, the lightemission control line 153 including the operation control gate electrode155 e and the light emission control gate electrode 155 f, the drivinggate electrode (the first storage capacitive plate) 155 a, and thebypass control line 158 are formed on the first gate insulating layer141.

The second gate insulating layer 142 covering the gate wires 151, 152,153, 155 a, 155 b, 155 c, 155 d, 155 e, 155 f, and 158 and the firstgate insulating layer 141 is formed thereon. The data wires 171, 172,174, 175, 178, and 179 including the data line 171, the driving voltageline 172 including the second storage electrode 178, the first dataconnecting member 174, the second data connecting member 175, and thethird data connecting member 179 are formed on the second gateinsulating layer 142.

The data line 171 is connected to the switching source electrode 136 bthrough the contact hole 62 formed in the first gate insulating layer141 and the second gate insulating layer 142. The first data connectingmember 174 is respectively connected to the initialization drainelectrode 137 d, the driving gate electrode 155 a, and the first storageelectrode 157 through the contact holes 63, 61, and 67 formed in thefirst gate insulating layer 141 and the second gate insulating layer142. Also, the second data connecting member 175 is connected to theinitialization source electrode 136 d and the bypass drain electrode 137g through the contact hole 64 formed in the first gate insulating layer141 and the second gate insulating layer 142. The third data connectingmember 179 is connected to the light emission control drain electrode137 f through the contact hole 66 formed in the first gate insulatinglayer 141 and the second gate insulating layer 142.

In this case, a thickness d1 of the second gate insulating layer 142positioned between the first storage electrode 157 and the secondstorage electrode 178 forming the storage capacitor Cst is less than athickness d2 of the second gate insulating layer 142 at other positions.By using a half-tone mask without a separate mask, the thickness d1 ofthe second gate insulating layer 142 can be formed to be less than thethickness d2 of the second gate insulating layer 142. Accordingly, thestorage capacitance of the storage capacitor maximized.

The interlayer insulating layer 160 covering the data wires 171, 172,174, 175, 178, and 179 and the second gate insulating layer 142 isformed thereon. The passivation layer 180 covering the interlayerinsulating layer 160 is formed thereon. The pixel electrode 191 and theinitialization voltage line 193 are formed on the passivation layer 180.The third data connecting member is connected to the pixel electrode 191through the contact hole 81 formed in the passivation layer 180. Thesecond data connecting member 175 is connected to the initializationvoltage line 192 through the passivation layer 180.

The pixel definition layer 350 covering the passivation layer 180, theinitialization voltage line 192, and the edge of the pixel electrode 191is formed thereon. The pixel definition layer 350 has the pixel opening351 exposing the pixel electrode 191. The organic emission layer 370 isformed on the pixel electrode 191 exposed by the pixel opening 351, andthe common electrode 270 is formed on the organic emission layer 370.

While the inventive technology has been described in connection withwhat is presently considered to be practical exemplary embodiments, itis to be understood that the disclosure is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An organic light-emitting diode (OLED) display,comprising: a substrate; a scan line formed over the substrate and thattransfers a scan signal; a data line and a driving voltage line thatrespectively transfer a data voltage and a driving voltage and that arethrilled over the substrate; a switching transistor that includes aswitching gate electrode electrically connected to the scan line, aswitching source electrode electrically connected to the data line and aswitching drain electrode configured to output the data voltage; adriving transistor that includes a driving gate electrode, a drivingdrain electrode, and a driving source electrode; and a connecting memberdisposed on a same layer as the driving gate electrode, wherein thedriving voltage line includes a first driving voltage line that extendsin a first direction and a second driving voltage line that extends in asecond direction crossing the first direction, wherein the first drivingvoltage line in the first direction and the second driving voltage linein the second direction are formed as a whole, wherein the data lineincludes a first data line and a second data line separated from thefirst data line, wherein the connecting member electrically connects thefirst data line to the second data line, wherein a bottom surface of thefirst driving voltage line and a bottom surface of the second drivingvoltage line directly contact a same layer, wherein the first data lineand the second data line are disposed at a same layer as the seconddriving voltage line, and the connecting member crosses and overlaps thesecond driving voltage line, and wherein the bottom surface of theconnecting member directly contacts a same layer as a bottom surface ofthe switching gate electrode and the driving gate electrode.
 2. Thedisplay of claim 1, further comprising: a semiconductor layer disposedon the substrate and including a switching channel and a driving channelseparated from each other; and a first gate insulating layer at leastpartially covering the semiconductor layer, wherein the switching gateelectrode and the driving gate electrode are disposed on the first gateinsulating layer and at least partially overlap the switching channeland the driving channel, respectively.
 3. The display of claim 2,wherein the driving channel has at least one curved portion.
 4. Filedisplay of claim 1, further comprising: a storage capacitor thatincludes a first storage electrode and a second storage electrode, andan OLED electrically connected to the driving drain electrode.
 5. Thedisplay of claim 4, wherein the second storage electrode and the drivinggate electrode at least partially overlap each other.
 6. The display ofclaim 4, further comprising: a second gate insulating layer that atleast partially covers the switching gate electrode, the driving gateelectrode, and the connecting member; interlayer insulating layer thatat least partially covers the data line and the driving voltage line;and a passivation layer formed between the interlayer insulating layerand the OLED, wherein the data line and the driving voltage line areformed between the second gate insulating layer and the interlayerinsulating layer.
 7. The display of claim 4, further comprising: aninitialization voltage line; and a transistor that initializes an anodeof the OLED and that includes a gate electrode, a source electrodeconnected to the anode of the OLED, and a drain electrode connected tothe initialization voltage line.
 8. The display of claim 7, furthercomprising: a control line connected to the gate electrode of thetransistor that initializes the anode of the OLED.
 9. An organiclight-emitting diode (OLED) display comprising: a substrate; a data lineand a driving voltage line each formed over the substrate and thatrespectively transfer a data voltage and a driving voltage; a drivingtransistor that includes a driving drain electrode, a driving gateelectrode, and a driving source electrode; and a connecting memberdisposed on a same layer as the driving gate electrode, wherein thedriving voltage line includes a first driving voltage line that extendsin a first direction and a second driving voltage line that extends in asecond direction crossing the first direction, wherein the first drivingvoltage line in the first direction and the second driving voltage linein the second direction are connected to and cross each other, whereinthe data line includes a first data line and a second data lineseparated from the first data line, wherein the connecting memberelectrically connects the first data line to the second data line,wherein a bottom surface of the first driving voltage line and a bottomsurface of the second driving voltage line directly contact a samelayer, wherein the first data line and the second data line are disposedat a same layer as the second driving voltage line, and the connectingmember crosses and overlaps the second driving voltage line, and whereinthe bottom surface of the connecting member directly contacts a samelayer as a bottom surface of the driving gate electrode.
 10. The displayof claim 9, further comprising: a semiconductor layer disposed on thesubstrate and including a driving channel; and a first gate insulatinglayer at least partially covering the semiconductor layer; wherein thedriving gate electrode is disposed on the first gate insulating layerand at least partially overlaps the driving channel.
 11. The display ofclaim 10, further comprising: a storage capacitor that includes a firststorage electrode and a second storage electrode, and an OLEDelectrically connected to the driving drain electrode.
 12. The displayof claim 11, further comprising: a second gate insulating layer that atleast partially covers the driving gate electrode, and the connectingmember; an interlayer insulating layer that at least partially coversthe data line and the driving voltage line; and passivation layer formedbetween the interlayer insulating layer and the OLED, wherein the dataline and the driving voltage line are formed between the second gateinsulating layer and the interlayer insulating layer.
 13. The display ofclaim 12, wherein the second storage electrode and the driving gateelectrode at least partially overlap each other.
 14. The display ofclaim 12, wherein the driving channel has at least one curved portion.15. The display of claim 12, further comprising: a initializationvoltage line; and a transistor that initializes an anode of the OLED andthat includes a gate electrode, a source electrode connected to theanode of the OLED, and a drain electrode connected to the initializationvoltage line.
 16. The display of claim 15, further comprising: a controlline connected to the gate electrode of the transistor that initializesthe anode of the OLED.